The present invention relates to a semiconductor optical modulator, and more particularly to improvement of the modulation speed thereof.
Semiconductor optical modulators for optical data processing and optical communication use are now being developed very actively. Among them, a voltage-driven semiconductor optical modulator of extremely high response speed which utilizes the electrooptic effect or electro-absorption effect is attracting attention as a high-speed modulator.
In this case, there has been a strong demand for a semiconductor optical modulator which is capable of high-speed modulation without the necessity of raising the modulating voltage, but no satisfactory proposals have been made up to now.